I'm sorry about your loss of Betty. Do you think you'd be happier with no cats? No shame in that. If so, maybe finding a new home for each is the best thing to do.
Or if you think Camille will end up a good fit for you, find a home for just Isis. That might not be too difficult since her clinginess could be appealing to a lot of cat people. Will you be disappointed if Camille never ends up an affectionate cat?
I expect that Camille and Isis would eventually find some sort of equilibrium, but possibly not one that is your idea of life with cats.